The Problem: It is estimated that about 1,200 new cases of adenoid cystic carcinoma (ACC) are diagnosed each year in the United States. These tumors are characterized by relentless growth and frequent recurrence. As a consequence, the 15-year survival rate for these patients is unacceptably low (40%). Since no drug has been approved for ACC, the primary treatment still is radical surgery, which is typically associated with high morbidity and poor quality of life. The lack of cell lines and mouse models has been identified as major roadblocks for the discovery of new therapies for ACC. Improvements in the survival of patients with ACC are likely to come from studies performed in animal models that mimic the human tumor microenvironment and enable the discovery of safe and effective mechanism-based therapies for this malignancy. Hypothesis: We recently developed a method to generate human ACC cell lines that is consisted of culturing cells retrieved from surgical specimens for 7-10 days in ultra-low attachment plates. Temporary exposure to non-adherent conditions eliminates stromal cells by anoikis and purifies cultures of tumorigenic ACC. Here, we will use our new ACC cell lines to develop a method for generation of xenograft tumors with humanized vasculature that is optimized for developmental therapeutics studies. The ACC xenograft model will be used to evaluate the effect of novel small molecule inhibitors of the MDM2/Bcl-2 signaling axis in pre-clinical trials. Notably, the oncoproteins MDM2 and Bcl-2 protect tumor cells against apoptosis, correlate with the aggressiveness of ACC, and are likely involved in resistance to chemotherapy. The underlying hypothesis of this work is that therapeutic inhibition of the MDM2/Bcl-2 signaling axis sensitizes adenoid cystic carcinomas to chemotherapy in pre-clinical models of ACC. To address this hypothesis, we propose the following aims: Specific Aim #1: To develop and characterize a xenograft model of adenoid cystic carcinoma with humanized vasculature that is suitable for pre-clinical trials. Specific Aim #2: To define the effect of therapeutic inhibition of the MDM2/Bcl-2 signaling axis on adenoid cystic carcinoma growth, angiogenesis, and recurrence. Specific Aim #3: To determine the effect of therapeutic inhibition of the MDM2/Bcl-2 signaling axis on adenoid cystic carcinoma resistance to a conventional chemotherapeutic drug (Cisplatin). Significance: This proposal is centered on mechanistic studies and pre-clinical trials with novel small molecule inhibitors of the MDM2/Bcl-2 pathway using a unique xenograft model of ACC with humanized vasculature. Small molecule inhibitors of MDM2 and Bcl-2 have been well tolerated by patients in Phase I and II trials. Therefore, successful outcome of the studies proposed here can rapidly be followed by a clinical trial testing these drugs in patients with ACC. Our research team is fully committed to the development of a mechanism- based therapy that will enhance the survival and quality of life of patients with adenoid cystic carcinoma.